Description of the Prior Art
Conventionally, a brake disk is single-piece. An outer ring of the brake disk is for a caliper to clamp thereon to brake, and a central portion of the brake disk is for being comovably connected with a hub. However, in this type of structure, the heat produced during the braking process transmits through the brake disk to the hub and influences the function of a brake.
Therefore, a two-piece brake disk is provided, including an inner disk for being connected with a hub and an outer disk for a caliper to clamp thereon. A center of the outer disk is formed with an opening for the inner disk to be arranged therein, the outer disk and the inner disk are fixed by a plurality of positioning members so as to reduce an amount of heat which is produced during the braking process transmitting to the hub; wherein a brake disk as disclosed in TW451855, TWI318188, TWM473983 and TWM473984 has an outer disk and an inner disk which overlap with each other, and a positioning member is disposed through the outer and inner disks. In this type of brake disk, the outer and inner disks need to be perforated respectively, and a contact area of the outer and inner disks is still great, so the heat insulation effect is not preferable. In addition, the inner and outer disks are fixed to each other only by the positioning member, so the structural strength is weak.
Besides, a floating brake disk as disclosed in TW335113, TWI404643, TWM243588, TWM271985, TWM306566, TWM386212, TWM409216 and TWM451445 is further provided, including an inner disk and an outer disk. The inner disk and the outer disk are provided with a recess or a U-shaped portion respectively, each recess of the inner disk and each recess of the outer disk correspond to each other to form a through hole, and a positioning member is disposed through the through hole to fix the inner and outer disks. This type of brake disk is greater than the above-mentioned brake disks in heat insulation effect. However, because the positioning member is sandwiched between the inner and outer disks, the heat may transmit to the inner disk through the positioning member. In addition, to prevent the inner and outer disks from rotating relative to each other, the recess or the U-shaped portion have to be designed specifically to be engageable with each other. If there are dimensional errors, the brake disk will be unusable. In addition, after being used for a long time, an outer edge of the recess may be abraded seriously, and the structural strength and stability of the brake disk may be influenced.
In addition, US 2015/0047932 disclosed a floating brake disk whose inner disk and outer disk not overlap. However, the opening of the recessed portion of the inner disk is smaller than the maximum width of the protruding portion of the outer disk, so the protruding portion cannot enter the recessed portion along the radial direction. Thus, it is inconvenient that the inner disk can only be installed onto the outer disk along the axial direction.
Besides, US D721309 disclosed an outer disk whose protruding portion has two legs. However, the protruding portion is V-shaped so that the engaging hole is located at the intersection of the two legs. As a result, too much stress concentrates on the intersection of the two legs.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.